Influence of desynchronized circadian rhythm on working memory, concentration and divided attention on pink collar shift workers of a tertiary care hospital: A comparative cross-sectional study

INTRODUCTION

Circadian rhythm is a biological rhythm having an endogenous free-running period lasting about 24 h, is entrain able and can keep up periodicity over the physiological temperature range despite changing kinetics.^[1] Information regarding daytime is relayed through the eyes to the suprachiasmatic nucleus (SCN) of the hypothalamus, the biological clock and through those clocks in the rest of the body like the sleep-wake cycle may be synchronized. The pineal gland on receiving inputs from SCN secretes melatonin that modulates circadian activity.^[2,3] Hypothalamus and reticular activating system mediate circadian rhythm at consciousness state.^[4] The sleep-wake cycle is necessary to replenish and heal the body for its proper functioning. Health care setup demands nonstandard working hours to ensure continuity of care and managing critically ill patients, making it imperative for shift workers to sacrifice their sleep and sleeping in the normal rising phase of the circadian rhythm, against environmental zeitgebers, promoting wakefulness; difficulty falling asleep for long periods; because of which sleep duration is reduced, sleep interruption becomes frequent, perceived as less restorative sleep, inducing increased sleepiness during the following night shift.^[5] The prefrontal, frontal cortex and thalamus are found to show a significant decrease in metabolic energy consumption in sleep-deprived states.^[6] Attention and working memory being related to these areas of brain, are vulnerable to sleep deprived states. Studies have shown that night shift work can cause fatigue, which reduces the cognitive and executive performance of workers and doing successive shifts risk increases by about 6% on the second night, 17% by the third night and 36% by the fourth night.^[7,8] Fatigue remains the major source of nurses’ errors in administering medication.^[9] Studies have also found that the ability to divide attention between multiple tasks is impaired in sleep deprivation,^[10] while some others did not show any association between the two states the role of high cognitive engagement and motivation related to simple attention tasks.^[11] In our study, we assumed that for a high cognition and attention-demanding job of a health care worker, divided attention should show greater impairment during sleep deprivation and merely increased effort and cognitive resources recruitment might be insufficient to compensate fully. Imaging studies in sleep-deprived have shown reduced alertness, impaired attention, working memory, logical reasoning, and decision making.^[12] Desynchronized circadian rhythm also causes significant health problems among them.^[13] Working memory, concentration, divided attention and making quick decisions for patient management which are of utmost importance become questionable. Sleep deprivation has been shown to affect working memory and decision making,^[14] while others found it to remain stable for higher-order executive functions in even sleep-deprived conditions due to a generation of motivation and interest, leading to a compensatory effort to do good.^[15] This could be true as health workers due to indulgence in such a noble profession, where there is an emotional connection with the patients during the continuous act of serving them and a positive motivational drive to treat them as soon as possible. Furthermore, sleep, distress, and fatigue-related disorders of health workers are still underestimated.^[16] Health care demands workers to be at an acceptable cognitive level to fulfill the high level of responsibilities and to deal with workplace stressors, including high workload, demanding work hours and making critical judgments.^[17] Adolescence and young adulthood are the period of development in which there is high reporting of cognitive and affective disorders such as anxiety and depression^[18] and these have been associated with cognitive deficits such as memory, attention and executive performance^[19] and have been shown to persist with remissions^[20] with poor neuropsychological performance and have been linked to poor outcomes.^[21] Hence, there is a need to identify targets for suitable intervention at an early stage as one factor that could potentially be associated with cognitive impairment is sleep and desynchronized circadian rhythm. Theories and hypothesis regarding how disordered sleep patterns and circadian rhythm misalignment can affect neurocognitive abilities are evolving rapidly with a better understanding of the neurobiology of sleep-wake regulation and also the conflicting nature of research-based evidence regarding the subject, possibly due to differences in the extent of sleep deprivation and the cognitive tasks used across studies, and paucity of data in the young adult population in Indian context provides a platform that we should intrigue the topic and study in-depth about it.

MATERIALS AND METHODS

RESULTS

DISCUSSION

The present study was conducted on pink collar shift workers in the health care setup of KLE Hospital to assess the effects of desynchronized circadian rhythm on working memory, concentration, and divided attention and comparing them with age- and gender-matched daytime working controls. No significant difference was observed in the ROCF copy test among the two groups [Figure 1]; although, shift workers’ mean score was low in comparison to controls. The possible explanation for not significant ROCF copy test results could be the correct fundamental approach adopted by the participants by organizing the stimulus figure into meaningful perceptual units while copying it, that is, starting to copy figure with global external features and then the local internal details in the construction process. Working memory was significantly affected in shift workers which are contrary to the hypothesis; we made that pink collar health workers doing shift work, working memory component might not be affected due to indulgence in such a noble profession where there becomes an emotional connect with the patients during a continuous act of serving and curing them and a positive drive to treat them; as soon as, possible could be a positive drive of motivation for some. It is also contrary to some other studies which found WM performance remains stable for higher-order executive functions in even sleep-deprived condition due to the generation of motivation and interest, leading to a compensatory effort to perform well in those conditions.^[15] In the SDMT, shift workers’ mean correct score was lower, the mean error score was slightly higher, and the total score was significantly lower [Figure 2]; indicating that they have lower accuracy, while performing tasks involving concentration and attention have lower concentration, and a significantly lesser speed to performing a task. The results of our study are as per imaging studies in sleep-deprived showing reduced alertness, impaired attention, working memory, logical reasoning, and decision making,^[12] and studies showing that sustaining attention, ignoring task-irrelevant information, and doing multi-tasking effectively are also impaired during sleep deprivation.^[27] Most authors observed that fatigue related to night shifts can increase the risk of human errors and injuries and can negatively affect the quality of patient care.^[28] Results regarding divided attention are in accordance to our assumption that for a high cognition and attention demanding jobs like of a pink collar health care worker, divided attention should show greater impairment during sleep deprivation, merely increased effort and cognitive resources recruitment might be insufficient to compensate, and a majority of studies that have shown that ability to divide attention between multiple tasks is impaired in sleep-deprived conditions.^[10] In the ROCF recall test, shift workers score was significantly low [Figure 3]; indicating lower accuracy to perform a task, which is as per studies showing fatigue induced due to accumulation of sleep deprivation remains the major source of nurses’ errors in administering medication.^[9]

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Figure 1:

Rey–Osterrieth complex figure copy test showing mean scores of shift workers and daytime working controls.

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Figure 2:

(a) Symbol digit modality test showing mean of correct scores of shift workers and daytime working controls. (b) Symbol digit modality test showing mean of error scores of shift workers and daytime working controls. (c) Symbol digit modality test showing mean of total scores of shift workers and daytime working controls.

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Figure 3:

Rey–Osterrieth complex figure recall test showing mean scores of shift workers and daytime working controls.

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CONCLUSION

Caregivers, especially nurses in health setup need to deal with workplace stressors such as high workload, demanding working hours, making critical judgments about fluctuating clinical conditions of the patients, and play a pivotal role in immediate detection and initiating appropriate interventions, with constantly organizing and reorganizing their priorities even at heightened fatigue level, have to make emotional interactions with patients’ and their relatives, and to ensure patients’ safety. To effectively perform these roles, they need to possess psychomotor, affective, cognitive, and complex thinking abilities for planning a suitable course of action. The cognitive status of nurses also has important implications for understanding the origin of medical errors. Shift work done by them to meet health care demands is found to deteriorate their health and even putting patients’ life to risk. Hence, it becomes of utmost importance to take measures regarding the same. It could be done by doing proper health assessment of the employee before shift work, giving suitable rest breaks, insuring regular and predictable schedules, offering at least an 8-h gap between shifts by proper working hours management, and maintaining adequate lighting and temperature control in hospitals, by implementing ergonomics to reduce adverse effects of shift work, so that nurses, other health care workers, and paramedical staff can deliver proper and continuous care to the patients’ without significantly affecting themselves. It can be done by doing proper health assessment of the employee before shift work, giving suitable rest breaks, insuring regular and predictable schedules, offering at least an 8-h gap between shifts by proper working hours management, and maintaining adequate lighting and temperature control in hospitals, by implementing ergonomics to reduce adverse effects of shift work, so that nurses, other healthcare workers, and paramedical staff can deliver proper and continuous care to the patients’ without significantly affecting themselves.